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It is also important to note that, contrary to what many take for granted, higher viscosity in and of itself does not translate into better engine protection. Extensive testing has shown the opposite to be in fact true. As long as a lower-viscosity oil is formulated to resist evaporation and provide high film strength, this lighter oil will actually deliver more complete protection to the engine parts, since its more rapid circulation delivers both better lubrication per se, and far better cooling characteristics…a critical advantage, given that oil flow furnishes up to 30% of an engine’s cooling requirements. Prior to the introduction of synthetics, however, the problem of evaporation (and the resultant thickening of the remaining oil) was addressed primarily by increasing viscosity. In short, don’t be concerned with the relatively lower viscosity ratings of some synthetics. Syn lubes are a whole new ball game.
